Process for the preparation of oxalic acid esters from cesium oxalate

Abstract

Processes for producing a disubstituted oxalate are disclosed. The process includes contacting a cesium salt with one or more alcohols and carbon dioxide (CO2) under reaction conditions sufficient to produce a composition comprising a disubstituted oxalate.

1 . A process for producing a disubstituted oxalate, the process comprising contacting a cesium salt with one or more alcohols and carbon dioxide (CO 2 ) under reaction conditions sufficient to produce a composition comprising a disubstituted oxalate having a general structure of: 
       
         
           
           
               
               
           
         
         where R 1  and R 2  are each independently an alkyl group, a substituted alkyl group, an aromatic group, or a substituted aromatic group. 
       
     
     
         2 . The process of  claim 1 , wherein the reaction conditions comprise a temperature of 125° C. to 200° C. 
     
     
         3 . The process of  claim 1 , wherein the reactions conditions comprise a pressure of 2 MPa to 5 MPa. 
     
     
         4 . The process of  claim 1 , wherein the cesium salt is cesium oxalate. 
     
     
         5 . The process of  claim 4 , wherein the cesium oxalate is obtained by contacting  1 ) CO 2  and carbon monoxide (CO), under reaction conditions sufficient to form a composition comprising the cesium oxalate 
     
     
         6 . The process of  claim 5 , wherein the reaction conditions for obtaining the cesium oxalate comprise a reaction temperature of 200° C. to 400° C. 
     
     
         7 . The process of  claim 5 , wherein the reaction conditions for obtaining the cesium oxalate comprise providing carbon dioxide at a pressure of 2.0 MPa to 3.0 MPa, and providing carbon monoxide at a pressure of 1.0 MPa to 3 MPa. 
     
     
         8 . The process of  claim 7 , wherein the carbon dioxide is contacted with the cesium carbonate at a reaction temperature of 200° C. to 400° C. for at least 1 hour to obtain a cesium carbonate/carbon dioxide reaction mixture, and contacting the cesium carbonate/carbon dioxide reaction mixture with the H 2  at the reaction temperature. 
     
     
         9 . The process of  claim 8 , wherein formation of sodium formate is inhibited. 
     
     
         10 . The process of  claim 5 , wherein the reaction conditions for obtaining the cesium oxalate comprise providing CO at a pressure of 2 MPa to 6 MPa, preferably about 2 MPa, and providing O 2  at a pressure of 0.05 MPa to 5 MPa. 
     
     
         11 . The process of  claim 5 , further comprising isolating the cesium oxalate salt from the product stream prior to converting it to the disubstituted oxalate. 
     
     
         12 . The process of  claim 5 , wherein the process is a single reactor synthesis such that cesium oxalate is generated in situ and then contacted with the one or more alcohols and additional CO 2  to produce the disubstituted oxalate. 
     
     
         13 . The process of  claim 1 , wherein R 1  and R 2  each independently comprise 1 to 20 carbon atoms. 
     
     
         14 . The process of  claim 13 , wherein R 1  and R 2  are each methyl groups. 
     
     
         15 . The process of  claim 1 , further comprising isolating the disubstituted oxalate from the product stream. 
     
     
         16 . The process of  claim 15 , further comprising reacting the disubstituted oxalate under conditions sufficient to form oxalic acid or ethylene glycol. 
     
     
         17 . A composition for producing a disubstituted oxalate, the composition comprising a cesium salt, carbon dioxide, carbon monoxide, and an alcohol. 
     
     
         18 . The composition of  claim 17 , wherein the alcohol is methanol and the disubstituted oxalate is dimethyl oxalate. 
     
     
         19 . A disubstituted oxalate produced by the process of  claim 1 . 
     
     
         20 . The disubstituted oxalate of  claim 19 , wherein the disubstituted oxalate is dimethyl oxalate.